If you do not pick up your boyfriend's belongings within the 30-day window, they will most likely be boxed up and placed in storage at the facility rather than discarded or donated immediately.
Correctional facilities keep inmate property in storage for a reasonable period because they understand that circumstances sometimes prevent timely pickup and because the property belongs to the inmate who will eventually need it. The storage arrangement is not indefinite and facilities do prefer that family members collect belongings to avoid the accumulation of boxes taking up storage space, but missing the 30-day window does not automatically mean everything is lost.
The property will generally be held until your boyfriend is released, at which point he can collect it himself or make arrangements for it to be picked up at that time. Some facilities, particularly federal ones, will ship inmate property to a designated home address rather than storing it indefinitely, which resolves the situation without requiring anyone to make a trip to the facility.
If the 30-day window is going to be a problem due to distance, transportation, or other circumstances, call the facility and explain the situation. Many facilities will extend the pickup window when there is a legitimate reason and the request is made respectfully before the deadline passes rather than after.
The most important thing is not to ignore the notice entirely. Communicating with the facility about your situation keeps the property secure and ensures your boyfriend has access to his belongings when this situation resolves.